Polyarylethersulfone compositions exhibiting reduced yellowness and high light transmittance properties and articles made therefrom

ABSTRACT

A polyarylethersulfone polymer composition comprising a polyarylethersulfone having reduced yellowness and high light transmittance is provided. The composition includes an organic phosphorous-containing compound and at least one of the following two additives: a colorant, and an optical brightener. The polyarylethersulfone composition of the present invention is used to form molded articles suitable for food and beverage service, medical components, and lighting components.

CROSS REFERENCE TO PROVISIONAL APPLICATIONS

This application claims priority from U.S. provisional patentapplication Ser. No. 60/372,079; filed Apr. 15, 2002, the entiredisclosure of which is incorporated herein by reference.

TECHNICAL FIELD

This invention is directed to polyarylethersulfone compositions with lowyellowness index and high light transmittance, and articles made fromthe polyarylethersulfone compositions, such as steam sterilizablemedical components, food and beverage containers, including hot beveragestorage containers and baby bottles, and lighting components.

BACKGROUND OF THE INVENTION

Polyarylethersulfones (PAES) are a commercially important family of highperformance, high temperature amorphous thermoplastics. These polymersare of interest to many industries because of their combination of highheat resistance, hydrolysis resistance in steam and hot waterenvironments and good overall chemical resistance. Another reason thesepolymers are of great commercial utility, is because in addition tooffering the stated high performance attributes, they are alsotransparent, unlike most semi-crystalline materials which are also usedin high temperature applications.

Polyarylethersulfones, which include polyethersulfone orpolyphenylsulfone can be produced by a variety of methods. For exampleU.S. Pat. Nos. 4,108,837 and 4,175,175 describe the preparation ofpolyarylethers and in particular polyarylethersulfones. Several one-stepand two-step processes are described in these patents, which patents areincorporated herein by reference in their entireties. In theseprocesses, a double alkali metal salt of a dihydric phenol is reactedwith a dihalobenzenoid compound in the presence of sulfone or sulfoxidesolvents under substantially anhydrous conditions. In a two-stepprocess, a dihydric phenol is first converted, in situ, in the presenceof a sulfone or sulfoxide solvent to the alkali metal salt derivative byreaction with an alkali metal or an alkali metal compound.

The transparency of polyarylethersulfones allows uses such as lids andcovers for surgical and dental instrument sterilization trays which haveto undergo steam autoclave sterilization. Other uses include medicalresearch lab animal cages, dairy processing equipment, particularlymilking machine components. Food and beverage uses also include usessuch as coffee serving carafes and containers, microwave cookware,covers for cookware containers and doors and windows for appliances,such as rotisserie grills. The inherent flammability resistance and lowsmoke release characteristics of polyarylethersulfones, particularlythose of polyphenylsulfone, make this polymer of great interest andutility to the mass transit industry where low heat release oncombustion and low toxic smoke emission properties of components used inpassenger compartments are of utmost importance. The aircraft industryin particular has capitalized on the low flammability and low smokeattributes of polyphenylsulfone for many years using this resin in avariety of cabin interior components.

While the polyarylethersulfones are transparent polymers, they doexhibit a yellow or amber cast. This yellow/amber cast is undesirable ina number of the uses described above. In most cases it is toleratedbecause of the lack of any viable material alternatives. In some othercases, such as in consumer oriented applications, where aesthetics aremore important, the yellow or amber cast is unacceptable. Consumeroriented hot food or hot beverage service items like tableware and babybottles are examples of such color and appearance sensitiveapplications. The key features of polyarylethersulfones in theseapplications are: good physical/mechanical integrity at hightemperatures, hot water resistance as well as resistance to cleaningagents, and food contact safety by virtue of the chemical inertness ofthe resin under conditions of use.

Commercially important polyarylethersulfones include polyethersulfone(PES) and polyphenylsulfone (PPSI). PES and PPSU have very high glasstransition temperatures (˜220° C.) and comprise the following repeatingunit structures:

Polyethersulfone

Polyphenylsulfone

The average number of repeat units, n, per polymer chain of the abovepolymers is generally greater than 30 and more typically greater thanabout 40 to ensure sufficiently high molecular weight for robustphysical and mechanical integrity of the polymers when fabricated intostructural components.

As stated above, one of the limitations of PAES resins inconsumer-related uses stems from the resins' yellow cast in theirnatural form. The yellowness in the natural resin can have varyingdegrees depending on a number of factors. However, in most cases it isaesthetically unacceptable. The present practice to neutralize or maskyellowness in polyarylethersulfones has so far been limited to theaddition of a violet or deep blue dye. The dye is effective at maskingyellowness, but it produces a “smoky” appearance with a substantialattendant reduction in visible light transmittance.

For a molded, transparent, food and beverage handling product to beaesthetically appealing, it is generally accepted that it must meetthree optical property requirements:

-   -   1. A low yellowness index, as commonly measured by ASTM method        D-1925, is needed. A yellowness index less than about 60,        preferably less than about 40, and more preferably less than        about 30 for a molded article is generally desirable at an        article thickness of 0.1 inch. Yellowness index is a thickness        dependent property.    -   2. A high light transmittance as commonly measured by ASTM        method D-1003 is also a key requirement. Light transmittance        values greater than about 50% at 0.1 inch thickness are desired.        Light transmittance is also a thickness dependent property        although generally to a lesser extent than yellowness index. It        is commonly measured at a thickness of 0.1 inch (2.5 mm), so        that if the transmittance requirements are met at 0.1 inch        (2.5 mm) thickness, they will be automatically met at reduced        thicknesses.    -   3. A low haze as measured by ASTM method D-1003 is also a        requirement. Haze is the ratio of the diffuse light        transmittance to the total light transmittance through a        specimen and it generally needs to be below about 10 and        preferably below 6 for 0.1 inch (2.5 mm) thick test specimen.        Like yellowness index and light transmittance, haze is also        dependent on specimen thickness, so it is important to compare        haze between different materials only at comparable thicknesses        and specimen surface characteristics.

Historically, Union Carbide, Amoco, and then Solvay Advanced Polymers,LLC have measured and tracked the color of polyarylethersulfone polymersusing the internal parameter of color factor (CF). The plastics industryas a whole, on the other hand, uses yellowness index (YI) to quantifycolor of film and moldings. It is instructive to look first at these twoquantities and how they relate to each other.

Yellowness index and color factor are two different quantities from thestandpoint of the definition of the parameter. However, for practicalpurposes, they do correlate very well.

By definition, yellowness index (YI) is calculated from the equationbelow based on ASTM method D-1925:YI=[100(1.28X−1.06Z)]/Ywhere in the equation above, X Y and Z are the tristimulus transmittancevalues for red, green and blue light, respectively, in the CIE system.

Color Factor (CF) is defined as the following quantity:CF=270[(x+y)_(sample)−(x+y)_(air) ]/twhere x and y are the chromaticity coordinates obtained by normalizingthe X and Y tristimulus transmittance values. The chromaticitycoordinates x and y are calculated by the following equations:x=X/(X+Y+Z)y=Y/(X+Y+Z)

The X, Y and Z are the tristimulus transmittance componentscorresponding to red, green and blue light respectively based onilluminating the sample with a standard light source, such as illuminantC or illuminant D65 according to ASTM method D-1003. The variable t isthe sample thickness in inches. So, unlike YI, CF is independent ofthickness at least up to a molded component thickness of about 1 inch,which is one attractive aspect of the quantity. The 270 factor is anarbitrarily chosen factor intended primarily to bring the CF values intoa convenient range to work with. Based on studies conducted at SolvayAdvanced Polymers, YI and CF of polyarylethersulfones are very wellcorrelated (with a correlation coefficient >0.99) by the followingequation for measurements on 0.1 inch thick specimens:YI=0.19(CF)so that a color-factor of 100, for example, indicates a yellowness indexof approximately 19 on the same specimen.

As mentioned above, yellowness index, light transmittance and haze areall thickness dependent properties so that thickness needs to bereported along with these measurements. Preferably multiple thicknessesshould be measured to show the dependence of these properties onthickness over a practical range of thicknesses.

It is desirable to produce a PAES with a reduced CF and haze andincreased transmittance for molded consumer articles. To achieve lowcolor factors, technology improvements are necessary in either or boththe synthesis-process side and in the stabilization of the pelletssupplied to the customers for prevention of additional color generationduring melt fabrication into injection molded articles.

SUMMARY OF THE INVENTION

There exists a need in the polymer composition art for a hightemperature, high strength, chemically resistant, clarified polymercomposition that has a combination of high transmittance, low yellownessindex, and low haze. There exists a need in the thermoplastic moldingart for a high strength, high glass transition temperature polymercompositions with a low yellowness index.

These and other needs are met by certain embodiments of the presentinvention, which provide a polyarylethersulfone polymer compositioncomprising a polyethersulfone or polyphenylsulfone. The composition alsoincludes an organic phosphorous-containing compound and at least one ofthe following additives: a colorant and an optical brightener.

The earlier stated needs are also met by certain embodiments of thepresent invention which provide a polyarylethersulfone compositioncomprising a polyethersulfone or polyphenylsulfone; from about 30 toabout 3000 ppm of an organic phosphorous-containing melt stabilizer; andat least one of the following additives: from about 0.1 ppm to about 200ppm of a blue to violet dye; and from about 1 ppm to about 10,000 ppm ofan optical brightener.

The earlier stated needs are also met by certain embodiments of thepresent invention comprising a polyarylethersulfone polymer compositioncomprising a polyethersulfone or polyphenylsulfone. The compositionfurther comprises an organic phosphorous-containing compound, acolorant, and an optical brightener.

The earlier stated needs are further met by certain embodiments of thepresent invention consisting of a polyethersulfone or apolyphenylsulfone and an organic phosphorous-containing compound and atleast one of a colorant and an optical brightener.

The earlier stated needs are further met by certain embodiments of thepresent invention consisting of a polyethersulfone or apolyphenylsulfone, at least one organic phosphorous-containing compound,a colorant, and an optical brightener.

The earlier stated needs are further met by certain embodiments of thepresent invention consisting of a polyethersulfone or apolyphenylsulfone, an organic phosphite and/or organic phosphonite, ablue to violet dye, and an organic optical brightener.

The earlier stated needs are further met by certain embodiments of thepresent invention that include melt fabricated, injection molded,compression molded, extruded, blow-molded, hybrid injection-compressionmolded, or thermoformed articles made from a polyarylethersulfonepolymer composition comprising a polyethersulfone or apolyphenylsulfone. The composition includes an organicphosphorous-containing compound and at least one of the followingadditives: a colorant, and an optical brightener.

Suitable melt stabilization schemes have been identified that inhibitthermally induced color development during processing operations. Incertain embodiments of the present invention a melt stabilizationadditive is combined with trace amounts of a to blue to violet dyeand/or an optical brightener to offset all or part of the remainingyellowness in the resin. Reduced color factors, increased transmittance,and good overall aesthetics have been achieved on molded plaques basedon embodiments of this invention.

The instant invention addresses the longstanding limitation of yellowingin polyarylethersulfones thereby allowing modified compositions thatreach the clarity levels needed for aesthetically challengingapplications to be possible for the first time. The present inventionovercomes the long-standing limitations in polyarylethersulfones byenabling, for the first time, the production of low yellowness and lowhaze polyarylethersulfone with high light transmittance characteristicsover the visible spectrum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically contrasts light transmittance versus wavelength ofmolded polyarylethersulfone compositions of the present invention andmolded prior art polyarylethersulfone compositions.

DETAILED DESCRIPTION OF THE INVENTION

The present invention enables the production of moldedpolyarylethersulfone articles with improved light transmittance andreduced yellowness. The present invention provides lightweight,high-light transmittance, low yellowness food and beverage storagecontainers, medical components and components useful in mass transitinteriors. The present invention allows the production of light-weight,tough, aesthetically appealing food and beverage serving containers,such as microwave cookware and baby bottles, steam sterilizable andchemically resistant medical components such intravenous nutrientdelivery and drug delivery components and lids for steam sterilizablesurgical instrument containers. The present invention also allows forthe production of rigid and flexible packaging based onpolyarylethersulfones. The present invention further allows for theproduction of glazing. In addition, the present invention allows for theproduction of components used in lighting such as diffusers anddecorative covers, particularly those for use in mass transit interiorssuch as on buses, trains or commercial aircraft where the need forflammability resistance is critical. The present invention furtherallows high temperature handling and molding of polyarylethersulfonewithout the attendant decrease in light transmittance and increasedyellowing observed in prior art polyarylethersulfone compositions. Thesebenefits are provided by a polyarylethersulfone composition comprisingsmall amounts of additives selected from organic phosphorous-containingcompounds, optical brighteners, and blue to violet dyes.

This invention removes the yellow cast from polyethersulfone andpolyphenylsulfone compositions. The removal of the yellow cast isdesirable, or required for some consumer items like baby bottles whereaesthetics are important and where the consumer has become accustomed tothe “crystal clear” appearance of polycarbonate. The violet dye, ZIRSOil Violet™, has been used to mask the yellowness inpolyarylethersulfone resins. While this dye is effective at removingyellowness, it also significantly reduces light transmittance propertiesof the resin due to its strong absorption in the blue-green region ofthe spectrum. Alternatives to the ZIRS Oil Violet™ dye that willneutralize the yellow cast of the polyarylethersulfone compositionswithout adversely affecting light transmittance properties aredesirable.

This invention will be described in conjunction with specific examplesof polyarylethersulfone compositions. However, these are exemplary only,as the claimed invention is not limited to the specific examplesdescribed herein.

Certain embodiments of the invention disclosed herein rely on using amixture of additives comprised of: (1) an organic phosphorous-containingcompound added for the purpose of limiting further yellownessdevelopment in the composition as a result of melt processing of thecomposition during the blending process or during the subsequentfabrication process used by the fabricator or end user; (2) an opticalbrightener added for the purpose of enhancing light transmittance overthe visible spectrum; (3) one or more dyes in the blue to violet colorrange. The above-described additive system can be incorporated bymethods known in the art. Examples include melt blending by compoundingand dry blending of virgin resin pellets with concentrate pellets (alsoknown as a master batch) containing a high loading of the additives.

In the concentrate or master batch approach, a blend of the desiredadditives is melt compounded into the base PAES polymer at loadingssubstantially higher (e.g. 5 to 10 times) than the target levels ofthese additives to produce homogeneous pellets with a concentratedpresence of the additives. The pellets of the master batch are thentumble blended with virgin PAES pellets and injection molded or extrudedor otherwise melt fabricated into their final form. This approachaffords the benefit of eliminating yellowness increases that can becaused by melt compounding the entire formulation, as only theconcentrate/master batch (e.g. 10% of the resin) needs melt compoundingin this case.

This invention relates to polyarylethersulfone compositions that aremodified for reduced yellowness and increased light transmittance in thevisible spectrum to allow production of more aesthetically pleasingmolded articles with improved clarity characteristics. Through the useof certain embodiments of this invention, one can producepolyarylethersulfone molded articles exhibiting light transmittancevalues per ASTM D-1003 of >60% and yellowness indices <30 as measuredper ASTM D-1925, both tests being conducted on 0.1 inch (2.5 mm thickspecimens).

This invention relates to polyarylethersulfone compositions that are lowin color and yellowness and high in light transmittance over the visiblespectrum. Compositions according to certain embodiments of thisinvention comprise polyarylethersulfone to which is added from about 30ppm to about 3000 ppm of an organic phosphorous-containing meltstabilizer and at least one of the following additives:

-   -   1. from about 1 ppm to 10,000 ppm of an optical brightener, and    -   2. from about 0.1 to about 200 ppm of one or more blue to violet        dyes. The amount of the additives is based on the weight of the        polyarylethersulfone.

Certain other embodiments of the present invention comprise apolyethersulfone or polyphenylsulfone and from about 100 ppm to about1500 ppm of an organic phosphorous-containing melt stabilizer and atleast one of the following additives:

-   -   1. from about 10 ppm to about 1000 ppm of an optical brightener,        and    -   2. from about 1 ppm to about 20 ppm of one or more of blue to        violet dyes, based on the weight of the polyarylethersulfone.

Certain other embodiments of this invention further comprise apolyarylethersulfone to which is added from about 30 to about 3000 ppmof an additive selected from the group consisting of organic phosphitesand phosphonites and mixtures thereof, and from about 1 ppm to about10,000 ppm of an optical brightener and/or from about 0.1 to about 200ppm of one or more blue to violet dyes.

Other certain embodiments of the present invention comprise from about100 to about 1500 ppm of an additive selected from the group consistingof organic phosphites and organic phosphonites and mixtures thereof, andfrom about 10 to about 1000 ppm of an optical brightener, and/or fromabout 1 to about 20 ppm of one or more blue to violet dyes.

Additional certain embodiments of the instant invention comprise fromabout 200 to about 800 ppm of an additive selected from the groupconsisting of organic phosphites and organic phosphonites and mixturesthereof, and from about 50 to about 500 ppm of an optical brightener,and/or from about 2 to about 15 ppm of one or more blue to violet dyes.

Certain embodiments of the present invention include polyethersulfonecompositions that exhibit a light transmittance of at least about 60%and a haze of less than about 5% when measured on 0.1 inch thickspecimens using ASTM method D-1003. Certain other polyethersulfonecomposition embodiments of the present invention further exhibit 1) ayellowness index (YI) of less than about 30 as measured according toASTM D-1925 on 0.1 inch thick specimens, or 2) a color factor (CF) ofless than about 150.

Certain embodiments of the present invention include polyphenylsulfonecompositions that exhibit a light transmittance of at least about 50%and a haze of less than 5.5% when measured on 0.1 inch thick specimensusing ASTM method D-1003. Certain other polyphenylsulfone compositionembodiments of the present invention further exhibit 1) a yellownessindex (YI) of less than 54 as measured according to ASTM D-1925 on 0.1inch thick specimens, or 2) a color factor (CF) of less than 280.

The additive system included within the scope of this invention can beadded either by direct compounding or during the part fabrication stepthrough the use of a master batch containing a concentrated form of theadditive system.

Suitable polyarylethersulfones included in the scope of this inventioninclude polyethersulfone and polyphenylsulfone, and copolymers andmiscible blends thereof. Polyethersulfone is available commercially froma number of sources. The basic polyethersulfone polymer backbone isbased on the polycondensation reaction of 4,4′-dihalodiphenylsulfone,most typically 4,4′-dichlorodiphenylsulfone with4,4′-dihydroxydiphenylsulfone (bisphenol S) in a molar ratio close to1:1. Copolymers of polyethersulfone where a minor portion of thebisphenol S is substituted with one or more other aromatic dihydroxymonomer compounds are also within the scope of the definition of thepolyethersulfone that can be used in the practice of this invention. Theother aromatic dihydroxy monomers that can be used in conjunction withbisphenol S include but are not limited to: hydroquinone,4,4′-dihydroxydiphenyl (biphenol), bisphenol A, and4,4′-dihydroxydiphenylether. The minor aromatic dihydroxy monomercomponent, such as hydroquinone, can be used in molar ratios relative tothe bisphenol S of up to about 30/70 while the ratio of the4,4′-dihalodiphenylsulfone to the total combination of aromaticdihydroxy monomers used is maintained close to 1:1 on a molar basis. Anexemplary source of a polyethersulfone containing a minor aromaticdihydroxy monomer component is RADEL® A, available from Solvay AdvancedPolymers, LLC. RADEL® A polyethersulfone is the polycondensation productof 4,4′-dichlorodiphenylsulfone with 4,4′-dihydroxydiphenylsulfone andhydroquinone reacted in the molar ratios of about 1:0.75:0.25.Polyphenylsulfone is available as RADEL® R from Solvay AdvancedPolymers, LLC. Polyphenylsulfone is based on the polycondensationreaction of 4,4′-dihalodiphenylsulfone with 4,4′-dihydroxydiphenyl. Asmentioned with respect to the polyethersulfone, copolymers based onincorporation of a minor aromatic dihydroxy monomer component, up toabout 30 mole % with the 4,4′-dihydroxydiphenyl would fall with thescope of the definition of polyphenylsulfone that can be used in thisinvention.

Any organic optical brightener that is soluble in polyarylethersulfonesis suitable for use in the present invention. An optical brightener is acompound that absorbs light in the near UV region and re-emits orfluoresces the energy absorbed in the visible range. The specificorganic phosphites and organic phosphonites described herein should notbe construed as a limitation on the compounds that are within the realmof possible embodiments of the invention. There are no limitations onthe blue to violet dyes that can be used, except for the practicallimitations that such dyes must be soluble in the polyarylethersulfoneand must possess sufficient thermal stability to allow incorporationinto these high temperature polymers via melt compounding.

The present invention enables the production of moldedpolyarylethersulfone articles with improved light transmittance andreduced yellowing. The present invention allows the high temperaturehandling and molding of polyarylethersulfone without the attendantdecrease in light transmittance and increased yellowing observed inprior art polyarylethersulfone compositions

Organic phosphorous-containing melt stabilizers suitable for use in thepractice of this invention can be from the phosphite or phosphonitefamily or mixtures thereof. Suitable phosphites include mono and dialkylsubstituted aromatic phosphites. In certain embodiments of the presentinvention the phosphites are di-t-butyl substituted aromatic phosphites,such as tris(2,4-di-t-butyl-phenyl) phosphite. In other certainembodiments of the present invention suitable phosphites include thosecontaining the pentaerythritol moiety. These include compounds such as:bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite, and bis(2,4-dicumylphenyl) pentaerythritoldiphosphite. Aromatic phosphonites are also suitable in certainembodiments of this invention, particularly aromatic mono anddiphosphonites. A particularly suitable phosphonite istetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4′-diylbisphosphonite.In certain embodiments of this invention this phosphonite is used incombination with a phosphite from the above described phosphites. Incertain embodiments of this invention the phosphonite used incombination with the phosphonite is tris(2,4-t-butylphenyl)phosphite. Insuch mixtures the phosphonite is preferred to be the major component andthe phosphite the minor one. A stabilizer composition which fits thisdescription is sold commercially under the trademark Sandostab PEPQ™.Sandostab PEPQ™ has been found to be particularly well-suited for use inthe practice of this invention.

Some suitable organic phosphorous-containing melt stabilizers are listedin Table 1. Additional suitable organic phosphorous-containing meltstabilizers include Weston 618™, Weston TLP™, and Ultranox 626™available from General Electric Specialty Chemicals, Inc. Irgafos 168™is a phosphite available from Ciba Specialty Chemicals, Inc. Othersuitable organic phosphites include Doverphos S-9228™ which isbis(2,4-dicumylphenyl) pentaerythritol diphosphite available from DoverChemical.

Suitable optical brighteners and a dye are listed in Table 2. Calco OilViolet ZIRS™ is anthracenedione dye available from BASF. EastobriteOB-1™ and OB-3™ are bisbenzoxazole based optical brighteners availablefrom Eastman Chemical Co. The OB-3™ differs from the OB-1™ in that itincludes a small amount of blue dye pre-blended into it by the supplier.The OB-1™ does not contain such a dye.

TABLE 1 Selected phosphorous-containing melt stabilizers suitable foruse in the practice of this invention. Chemical Trade Name Chemical NameSupplier Structure Weston 618 ™ Distearyl pentaerythritol GE Specialty Idiphosphite Chemicals, Inc. Sandostab Mixture of three Clariant Corp. IIPEPQ ™ phosphonites and one phosphite Irgafos 168 ™ Tris(2,4-di-t-butylphenyl) Ciba Specialty III phosphite Chemicals, Inc. UltranoxBis(2,4-di-t-butyl phenyl) GE Specialty IV 626 ™ pentaerythritoldiphosphite Chemicals, Inc. Weston TLP ™ Trilauryl phosphite GESpecialty V Chemicals, Inc.

TABLE 2 A dye and optical brighteners suitable for use in the practiceof this invention. Chemical Trade Name Chemical Name Supplier StructureCalco Oil Violet 1-hydroxy-4-{(4- BASF VI ZIRS ™methylphenyl)amino)-9,10- anthracenedione Eastobrite OB-1 ™2,2′-(1,2-Ethenediyldi-4,1- Eastman VII phenylene)bisbenzoxazoleChemical Co. Eastobrite OB-3 ™ 2,2′-(1,2-Ethenediyldi-4,1- Eastman VIIphenylene)bisbenzoxazole Chemical Co.

The chemical structures of phosphites and phosphonites listed in Table1.

The composition and Stricture of PEPQ™:

The chemical structures of the violet dye and optical brighteners listedin Table 2.

In addition to the additives required for the practice of thisinvention, other additives can be incorporated to achieve other targetedperformance or processing attributes. These can include but are notlimited to: lubricants, mold releases, antistatic agents, UV absorbers,flame retardants, anti-fogging agents and matting agents.

Approaches investigated to provide improved yellowness masking andremoval include the use of optical brighteners, blue to violet dyes, theuse of a melt stabilizer to limit color rise during processing, andcombinations of these approaches. Polyethersulfone and polyphenylsulfoneformulations prepared are listed in Tables 3 and 4. The additives areadded in the amounts shown and the balance of the compositions is thepolyarylethersulfone. These formulations were prepared by meltcompounding on a 40 mm ZSK-40 Werner-Pfleiderer twin screw extruderusing a 4×3 mm hole die, a screw rpm of about 250, a throughput rate ofabout 200 lb/hr and a melt temperature of 380-390° C. in order tosimulate commercial scale production of these materials. Opticalproperties were measured according to the methods listed in Table 5 on2″×3″ injection molded color plaques that were 0.1 inch thick.

TABLE 3 Polyethersulfone compositions. Examples Components C1 C2 C3 C4C5 C6 1 RADEL ® A-200 NT 100% 100% balance balance balance balancebalance Calco Oil Violet — — 10 ppm — —  5 ppm  5 ppm ZIRS ™ EASTOBRITE— — — 100 ppm 200 ppm 200 ppm 200 ppm OB-3 ™ PEPQ ™ Stabilizer — — — — —— 500 ppm Comments Virgin Extruded — — — — — Control, Control NotExtruded

TABLE 4 Polyphenylsulfone compositions. Examples Components C7 C8 2 3 C9RADEL ® R-5000 NT 100% balance balance balance 100% ZIRS Oil of Violet ™—  5 ppm  5 ppm  8 ppm — EASTOBRITE OB-3 ™ — 200 ppm 200 ppm 400 ppm —PEPQ ™ Stabilizer — — 500 ppm 500 ppm — Comments Extruded — — — VirginControl Control, Not Extruded

The above 12 samples were injection molded into color plaques(2″×3″×0.10″) and step plaques at 3 thicknesses (0.13″, 0.10″ and0.70″). The step plaques were used for visual comparison between thedifferent materials while the flat color plaques were used to generateoptical properties. Optical properties measured included the following:% light transmittance, haze, color factor, yellowness index, X, Y, Ztristimulus coordinates. The optical properties were tested as describedin Table 5. Results are presented in Tables 6 and 7. The transmittanceof the molded sample plaques at a number of wavelengths spanning thevisible spectrum is provided in Tables 8 and 9. The light transmittanceversus wavelength is plotted for a number of Examples in FIG. 1. All thedata in Tables 6-9 and FIG. 1 are based on 0.1 inch thick sampleplaques.

TABLE 5 Test Methods Test Method Description/Conditions Yellowness IndexASTM D-1925 Nominal sample thickness = 0.1 in. Light Transmittance ASTMD-1003 Nominal sample thickness = 0.1 in. Haze ASTM D-1003 Nominalsample thickness = 0.1 in; A spectrophotometer was used rather than ahaze meter. Color Factor Test method described in Background Of TheInvention.

TABLE 6 Optical properties of Controls/Comparative Examples C1-C6 andExample 1. Examples Testing Information: C1 C2 C3 C4 C5 C6 1 Light 71.3956.63 52.36 60.24 60.54 59.13 62.68 Transmittance “Y” (%) X 68.64 55.3051.49 58.49 58.60 57.46 60.59 Z 54.69 45.94 49.70 48.72 48.55 50.9556.25 Color Factor 201.4 220.0 130.1 193.7 199.7 172.6 147.2 Yellowness38.76 41.63 25.04 38.31 38.66 32.83 28.38 Index Haze (%) 3.09 10.9 8.497.76 7.54 7.14 4.54

TABLE 7 Optical properties of controls/comparative examples C7-C9 andexamples 2 and 3. Examples Testing Information: C7 C8 2 3 C9 LightTransmittance “Y” 54.12 50.72 55.07 50.34 71.88 (%) X 52.70 49.06 53.0548.29 69.12 Z 31.39 32.61 36.87 37.24 56.11 Color Factor 332.8 302.0275.8 237.1 213.1 Yellowness Index 62.91 55.40 52.09 44.13 40.1 Haze (%)6.76 6.18 5.21 5.43 3.17

TABLE 8 Transmittance at different wavelengths of visible light forcontrols/ comparative examples C1-C6 and example 1. Examples Wavelength(nm) C1 C2 C3 C4 C5 C6 1 400 17.15 22.01 24.54 0.01 0.01 0.01 0.01 42029.67 29.28 32.69 21.23 16.76 20.93 20.61 440 41.05 35.54 39.29 39.5940.01 42.09 47.16 460 49.50 40.67 44.03 44.03 44.51 46.32 51.48 48055.62 44.54 47.18 48.34 48.65 50.07 55.29 500 61.77 48.83 49.66 52.2552.85 53.58 58.59 520 66.19 52.00 50.71 55.78 56.19 55.94 60.51 54069.71 54.72 51.04 58.69 58.90 57.66 61.62 560 73.51 58.02 51.64 61.4161.87 59.62 62.89 580 75.78 60.17 52.73 63.49 63.76 61.15 63.76 60076.95 61.51 54.34 65.46 65.38 62.75 65.28 620 79.36 63.92 58.30 67.2667.45 65.55 68.05 640 80.67 65.55 62.88 68.95 69.26 68.39 71.39 66081.58 66.77 66.94 70.56 71.12 71.04 75.07 680 82.62 68.11 70.10 71.7872.58 73.09 77.51 700 82.84 68.75 72.16 72.91 73.42 74.32 78.87

TABLE 9 Transmittance at different wavelengths of visible light forcontrols/ comparative examples C7-C9 and examples 2 and 3. ExamplesWavelength (nm) C7 C8 2 3 C9 400 5.28 0.01 0.01 0.01 18.02 420 13.827.75 9.01 6.30 31.00 440 22.04 24.58 27.97 29.16 42.41 460 28.62 30.5534.65 35.51 50.59 480 34.41 36.05 40.38 40.61 56.82 500 40.74 41.2845.88 44.99 62.38 520 46.85 46.01 50.44 48.00 66.98 540 51.86 49.2753.59 49.47 70.56 560 56.42 51.79 56.30 50.52 73.70 580 59.65 53.8058.25 51.31 75.95 600 62.01 56.13 60.40 53.33 77.63 620 64.97 59.4563.57 56.75 79.39 640 67.16 63.43 67.19 61.77 80.67 660 68.87 67.4670.96 67.83 81.63 680 70.52 70.33 73.61 71.92 82.51 700 71.58 72.4275.27 74.21 83.15

The data show that:

1. Molded polyethersulfone compositions according to the presentinvention have higher transmittance than extruded polyethersulfone (C2)and the polyethersulfone composition with only the dye additive (C3)over the range of visible wavelengths.

2. Molded polyethersulfone compositions with PEPQ™ melt stabilizer (e.g.Example 1) feature reduced yellowness indices in contrast to the virginand extruded polyethersulfone (C1, C2), compositions with only theoptical brightener additive (C4, C5), and compositions where both anoptical brightener and a dye are included but not a phosphorouscontaining melt stabilizer (C6).

3. Molded polyethersulfone and polyphenylsulfone compositions accordingto the present invention all show acceptable haze levels below 10%.

4. Molded polyphenylsulfone compositions according to the presentinvention (e.g. Example 2) feature lower yellowness indices thanextruded polyphenylsulfone (C7) while maintaining essentially the samelight transmittance across the visible spectrum.

5. Molded polyphenylsulfone compositions according to the presentinvention (Examples 2 and 3) have reduced haze relative to extrudedpolyphenylsulfone (C7) and a composition where both an opticalbrightener and a dye are included but not a phosphorous containing meltstabilizer (C8).

The data from the examples presented illustrate that PAES compositionsaccording to the present invention have the desired optical qualitiesnecessary for forming molded articles for aesthetically demanding enduses.

The embodiments illustrated in the instant disclosure are forillustrative purposes. They should not be construed to limit the scopeof the claims. As is clear to one of ordinary skill in this art, theinstant disclosure encompasses a wide variety of embodiments notspecifically illustrated herein.

1. A polyarylethersulfone polymer composition comprising: apolyphenylsulfone; an organic phosphorous-containing compound; and atleast one additive selected from the group consisting of: a blue toviolet dye; and an optical brightener, wherein said optical brighteneris a bisbenzoxazole.
 2. A polyarylethersulfone polymer compositioncomprising: a polyethersulfone or a polyphenylsulfone; from 30 ppm to3000 ppm of an organic phosphorous-containing melt stabilizer; and from0.1 ppm to 200 ppm of a blue to violet dye; wherein saidpolyethersulfone comprises the structural unit


3. The polyarylethersulfone polymer composition of claim 2, wherein thecomposition comprises: from 1 ppm to 20 ppm of the dye; and from 100 ppmto 1500 ppm of the melt stabilizer.
 4. A polyarylethersulfone polymercomposition comprising: a polyethersulfone or a polyphenylsulfone; anorganic phosphorous-containing compound; a blue to violet dye; and anoptical brightener.
 5. The composition according to claim 4, wherein thecomposition comprises a polyethersulfone comprising the structural unit


6. The composition according to claim 1, wherein the polyphenylsulfonecomprises the structural unit


7. The composition according to claim 4, wherein the compositioncomprises a polyphenylsulfone comprising the structural unit


8. The composition according to claim 1, wherein said compositionexhibits a light transmittance of at least about 60% and a haze of lessthan about 5% when measured on a 0.1 inch thick specimen using ASTMmethod D-1003.
 9. The composition according to claim 8, wherein saidcomposition has 1) a yellowness index (YI) of less than about 30 asmeasured according to ASTM D-1925 on a 0.1 inch thick specimen, or 2) acolor factor (CF) of less than about 150, wherein CF is defined by theequation:CF=270[(x+y)_(sample)−(x+y)_(air) ]/t wherein x and y are chromaticitycoordinates measured in transmittance mode and t is the sample thicknessin inches.
 10. The composition according to claim 6, wherein saidcomposition exhibits a light transmittance of at least about 50% and ahaze of less than 5.5% when measured on a 0.1 inch thick specimen usingASTM method D-1003.
 11. The composition according to claim 10, whereinsaid composition exhibits 1) a yellowness index (YI) of less than 54 asmeasured according to ASTM D-1925 on a 0.1 inch thick specimen, or 2) acolor factor (CF) of less than 280, wherein CF is defined by theequation:CF=270[(x+y)_(sample)−(x+y)_(air) ]/t wherein x and y are chromaticitycoordinates measured in transmittance mode and t is the sample thicknessin inches.
 12. The composition according to claim 1, wherein the organicphosphorous-containing compound is an organic phosphonite, optionally inmixture with an organic phosphite.
 13. The composition according toclaim 5, wherein the organic phosphorous-containing compound is anorganic phosphonite, optionally in mixture with an organic phosphite.14. The composition according to claim 7, wherein the organicphosphorous-containing compound is an organic phosphonite, optionally inmixture with an organic phosphite.
 15. The composition according toclaim 5, wherein said optical brightener is a bisbenzoxazole.
 16. Thecomposition according to claim 7, wherein said optical brightener is abisbenzoxazole.
 17. A melt fabricated article comprising thepolyarylethersulfone composition according to claim
 1. 18. An injectionmolded or compression molded article comprising the polyarylethersulfonecomposition according to claim
 1. 19. A hybrid injection-compressionmolded article comprising the polyarylethersulfone composition accordingto claim
 1. 20. An extruded article comprising the polyarylethersulfonecomposition according to claim
 1. 21. A blow-molded article comprisingthe polyarylethersulfone composition according to claim
 1. 22. Athermoformed article comprising the polyarylethersulfone compositionaccording to claim
 1. 23. A polyarylethersulfone polymer compositioncomprising: a polyethersulfone or a polyphenylsulfone; from 30 ppm to3000 ppm of an organic phosphorous-containing melt stabilizer; and from1 ppm to 10,000 ppm of a bisbenzoxazole optical brightener.